It is known, for remote actuation of valves, especially valves with angularly displaceable valve members, i.e. valve members which are brought from closed to open position and vice versa by a full rotation or a swinging movement, to provide electrically, pneumatically or other valve drivers. The valve driver is as a rule provided with an intervening part mounted upon the valve housing and generally also referred to as a housing, for example, as a connecting housing, which can be bolted onto the housing of the valve driver and to the body of the valve.
The output shaft of the valve driver and the actuating shaft of the valve member are usually coupled together in the connecting housing by a threaded connection, a pin or a plug and socket connection which have tolerances due to fabrication.
The valves generally must be capable of withstanding highly aggressive and corrosive substances and must be capable of maintaining the seal or tightness against high pressures. For these reasons, the valve can be provided with seal or other packings around the actuating shaft preventing the escape of fluid.
The packing can be compressed by a packing bushing, ring or sleeve and corresponding screws which adjust the position of the packing bushing or can be clamped by a central packing nut.
The packing bushing or nut can be braced directly against a pressure ring or washer which bears upon the packing or can compress the spring stack which bears against the packing bushing, washer or packing itself.
The central packing nut can have an external thread engaged with an internal thread which can be threaded onto the external thread of the valve shaft.
In practically all of the prior art constructions, the packing nut must be provided with a counternut to prevent involuntary loosening of the packing nut from the valve shaft. Security against loosening of the nut is also required since the entrainment of the nut with the shaft creates relative movement between the nut and the stationary packing rings. As a result of the valve requirements described above, the parts of the valve must be fabricated with relatively close tolerances and that applies as well to the coupling parts between the driver and the actuating shaft.
In the past, partly as a result of these high tolerance requirements and partly because it has not been possible to reliably prevent loosening of the packing nuts, the operation of such valves has required from time to time, time-consuming retightening of the packing nuts which has necessitated the interruption in valve service which generally results in the falling off in production.
Furthermore, conventional and earlier coupling arrangements between the valve driver and the valve of such an assembly has involved very high fabrication costs.